Соответствующая норма
Nigeria
Practice Relating to Rule 1. The Principle of Distinction between Civilians and Combatants
Nigeria’s Military Manual (1994) states: “The main aim for all commanders and individual combatants is to distinguish combatants and military objectives from civilian persons and objects at all times.”
According to the Report on the Practice of Nigeria, it is Nigeria’s opinio juris that the principle of distinction between combatants and civilians is part of customary international law. 
Report on the Practice of Nigeria, 1997, Chapter 1.1.
Nigeria’s Military Manual (1994) and Soldiers’ Code of Conduct state that combatants must “fight only combatants”. 
Nigeria, International Humanitarian Law (IHL), Directorate of Legal Services, Nigerian Army, 1994, p. 39, § 5(a); Code of Conduct for Combatants, “The Soldier’s Rules”, Nigerian Army (undated), § 1.
Nigeria’s Military Manual (1994) and Soldiers’ Code of Conduct state: “Civilian persons and objects must be spared.” 
Nigeria, International Humanitarian Law (IHL), Directorate of Legal Services, Nigerian Army, 1994, p. 39, § 5(c); Code of Conduct for Combatants, “The Soldier’s Rules”, Nigerian Army, undated, § 3.
The Report on the Practice of Nigeria confirms the existence of a norm of a customary nature prohibiting direct attacks against civilians and cites Nigeria’s Operational Code of Conduct in this respect. The report also states that, according to Nigeria’s opinio juris, the prohibition of direct attacks against civilians is part of customary international law. 
Report on the Practice of Nigeria, 1997, Chapter 1.4.